1. Field of the Invention
The present invention relates to capacitor assemblies for printed circuit boards, and more specifically to preventing damage to a printed circuit board and other nearby components that can be caused by capacitor failure.
2. Description of the Related Art
The failure of a capacitor or certain other components in an integrated circuit is usually accompanied by generation of heat in the failed capacitor or component. In older integrated circuit designs, the heat generated by the failure of a capacitor was generally not significant, and did not cause damage to adjacent components. When there was a concern that damage could result, additional space would be provided between components, the amount of insulation between the ground plane and the voltage plane would be provided, fault detection circuitry would be provided for the power supply, or other expensive and inefficient procedures would be used.
The trend over time has been for integrated circuit assemblies to become more compact and to be placed in closer proximity to other integrated circuits. For example, the spacing between integrated circuit cards in a server has decreased as the density of components on integrated circuit boards has increased. Likewise, the amount of materials used for forming the integrated circuit board, such as the insulation between the ground plane and voltage plane, has decreased, such that the ground plane and the voltage plane are now separated by insulation having less thickness than has been used in the past. As a result of these various changes, damage from failed components can now spread more readily to other components or adjacent integrated circuits.
For example, fires have occurred in servers or other computing equipment that were caused by the failure of a single capacitor, such as a tantalum capacitor. These fires resulted when the failure of the capacitor caused shorting between the ground plane and the voltage plane, which occurred when the insulation underneath the capacitor and between the ground plane and the voltage plane was damaged or degraded by heat generated from the failed capacitor. The server power supply was not configured to detect the short between the ground plane and the voltage plane, and thus continued to feed energy to the fault. As the current delivered to the failing capacitor and printed circuit board may have been within normal system operating ranges, detection of the fault would have required signal processing circuitry to detect signals indicative of fault, and may have been undetectable from the power supply by conventional means. The high energy level of the fault caused continued burning of the insulation, which spread to adjacent integrated circuit boards. In a short period of time, many integrated circuit boards were burning in the server, generating significant amounts of smoke. The smoke caused fire protection equipment in the computer room in which the server was housed to activate, thus damaging large amounts of equipment, causing the computing facility to shut down, causing loss of data and causing other damage and detrimental effects.
A component damage arrestor according to the invention is provided that prevents a damaged component from causing adjacent components to fail. The component damage arrestor uses the removal of the ground plane and voltage plane from the area adjacent to the capacitor to prevent shorting of the ground plane to the voltage plane when the component fails. In the disclosed embodiment, the component damage arrestor allows localized insulation damage to occur but prevents the damage from allowing the ground plane and the voltage plane to short together, so as to prevent sustaining the damage mechanism and expanding the damage.